https://www.youtube.com/watch?v=bF91tr6WiRw
By Alien Means is an unreleased track recorded at some point in 1988 at Paisley Park Studios, Chanhassen, MN, USA (the song was filed for copyright registration on 12 October 1988). Prince submitted the track to Madonna for inclusion on her fourth album Like A Prayer (which featured Prince on other tracks), but she turned it down, and it is unlikely that she ever recorded vocals for the track.
full article here http://squaremadonnaicongallery.altervista.org/madonna-prince/